package com.tbgov.util;

import lombok.extern.slf4j.Slf4j;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;

@Slf4j
public class MD5Util {
    private static final String ALGORITHM_MD5 = "MD5";

    public static String MD5(String s) {
        char[] hexDigits = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
        try {
            byte[] btInput = s.getBytes();
            // 获得MD5摘要算法的 MessageDigest 对象
            MessageDigest mdInst = MessageDigest.getInstance("MD5");
            // 使用指定的字节更新摘要
            mdInst.update(btInput);
            // 获得密文
            byte[] md = mdInst.digest();
            // 把密文转换成十六进制的字符串形式
            int j = md.length;
            char[] str = new char[j * 2];
            int k = 0;
            for (byte byte0 : md) {
                str[k++] = hexDigits[byte0 >>> 4 & 0xf];
                str[k++] = hexDigits[byte0 & 0xf];
            }
            return new String(str);
        } catch (Exception e) {
            log.error("MD5加密错误", e);
        }
        return null;
    }

    public static String getMD5(String srcTxt) throws NoSuchAlgorithmException, NullPointerException {
        if (srcTxt == null) {
            throw new NullPointerException("输入参数为 NULL!");
        }
        StringBuilder result = new StringBuilder();
        MessageDigest digest = MessageDigest.getInstance(ALGORITHM_MD5);
        digest.update(srcTxt.getBytes());
        byte[] byteRes = digest.digest();
        for (byte byteRe : byteRes) {
            result.append(byteHEX(byteRe));
        }
        return result.toString();
    }

    private static String byteHEX(byte ib) {
        char[] DigitNormal = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
        char[] ob = new char[2];
        ob[0] = DigitNormal[(ib >>> 4 & 0xF)];
        ob[1] = DigitNormal[(ib & 0xF)];
        return new String(ob);
    }

    public static String getMD5byBase64(String input) {
        try {
            MessageDigest digest = MessageDigest.getInstance(ALGORITHM_MD5);
            digest.update(input.getBytes());
            return Base64.getEncoder().encodeToString(digest.digest());
        } catch (NoSuchAlgorithmException ex) {
            log.error("MD5byBase64加密错误", ex);
        }
        return null;
    }

    // 支付使用
    public static String MD5Encode(String origin, String charsetName) {
        String resultString = null;
        try {
            resultString = origin;
            MessageDigest md = MessageDigest.getInstance("MD5");
            if (charsetName == null || "".equals(charsetName)) {
                resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
            } else {
                resultString = byteArrayToHexString(md.digest(resultString.getBytes(charsetName)));
            }
        } catch (Exception exception) {
            log.error("MD5Encode错误", exception);
        }
        return resultString;
    }

    private static String byteArrayToHexString(byte[] b) {
        StringBuilder resultSb = new StringBuilder();
        for (byte value : b) {
            resultSb.append(byteToHexString(value));
        }
        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n += 256;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    private static final String[] hexDigits = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};
}
